Compact abdominal exerciser

ABSTRACT

A compact portable abdominal exercise apparatus is provided and includes an upper body member slidingly received by a lower body member. A resistance member is attached between the upper body member and the lower body member to provide resistance to relative motion of the upper and lower body members in a first direction. The lower body member is adapted to engage a chair or other sitting platform, either between the legs of a user or on either side of the user&#39;s body adjacent a thigh. The size of the exercise apparatus positions the user in an ergonomic position that permits the user to perform oblique crunches downward and to either side, or forward if the lower body member is positioned between the user&#39;s legs, to exercise all of the abdominal muscles. A slideable cover protects the user from moving parts associated with the exercise apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Application No. 60/703,911 filed Jul. 28, 2005, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to exercise equipment utilizing elastic resistance members, and in particular to abdominal exercisers.

2. Description of Related Art

Compact abdominal exercisers that include resistive force have been known for forty years. Examples of abdominal exercisers include U.S. Pat. No. 4,863,162 issued Sep. 5, 1989 to Neckamm et al.; U.S. Pat. No. 5,046,726 issued Sep. 10, 1991 to Willem J. Van Straaten; U.S. Pat. No. 5,071,119 issued Dec. 10, 1991 to Martin W. Johnson; U.S. Pat. No. 5,232,425 issued Aug. 3, 1993 to Jack V. Miller and Ned Gvoich; U.S. Pat. No. 5,695,436 issued Dec. 9, 1997 to Ming-Chih Huang; and U.S. Pat. No. 6,712,742 issued Mar. 30, 2004 to William G. Suiter. All of these exercisers are designed to be used by crunching or bending in a forward direction. Moreover, the Van Stratten and the Miller and Gvoich patents all contain portions of the resistance mechanism that can easily be contacted by the body during exercise, which parts can pinch or snag on the body during use, particularly if used other than in a forward-bending direction. However, the abdominal muscles of the human body are designed for bending in directions other than the forward direction, such as sideways. Thus, the above exercisers cannot comfortably be used for exercising all the abdominal muscles.

The device of the Suiter patent has been commercially successful because the moving parts are all enclosed in a case, and it is very compact and easier to use than the other devices. However, it is designed to be operated by placing the lower portion on the user's thighs, and thus it cannot be easily used to do side-bending exercises. Moreover, it is relatively complex and therefore is relatively costly to build. Thus, an abdominal exerciser that can be easily used to exercise all the abdominal muscles is needed. Moreover, such a device would be even more desirable if it was compact and had all the parts of the resistance mechanism enclosed like the Suiter device, but was simpler and more economical to manufacture.

BRIEF SUMMARY OF THE INVENTION

The problems presented by traditional abdominal exercisers are solved by the systems of the present invention. An abdominal exerciser according to one embodiment of the present invention includes a lower body member adapted to engage a seating platform on which a user is seated and an upper body member adapted to engage a portion of the user above the abdomen. A constraint assembly connects the upper and lower body members to permit relative motion of the upper and lower body members in a first direction along a line connecting the body members and to prevent relative motion of the upper and lower body members in directions perpendicular to the first direction. A first anchor notch is operably associated with the lower body member, and a second anchor notch is operably associated with the upper body member. A resilient cord is provided and is connectable between the first and second anchor notches to provide resistance to relative motion of the upper and lower body members in the first direction. The abdominal exerciser is sized such that the length of the apparatus from a distal end of the lower body member to a proximal end of the upper body member permits oblique crunches when the lower body member engages the seating platform.

In accordance with another embodiment of the present invention, an abdominal exerciser is provided and includes a lower body member adapted to engage a seating platform on which a user is seated and an upper body member adapted to engage a portion of the user above the abdomen. The upper body member is connected to the lower body member such that relative motion of the upper and lower body members is permitted in at least a first direction along a longitudinal line connecting the body members and prevented in directions perpendicular to the first direction. A resistance member is operably attached to the upper body member and the lower body member to resist but not prevent relative motion of the upper and lower body members in the first direction. The resistance member is contained within a resistance cavity, and a protective cover is slidingly disposed on at least one of the upper and lower body members to substantially enclose the resistance cavity when the protective cover is placed in a closed position and to allow access to the resistance cavity when the protective cover is placed in an open position.

In accordance with another embodiment of the present invention, an abdominal exerciser is provided and includes a first body member having a first chamber at least partially surrounded along its length by a first wall having inner and outer surfaces. A plurality of rails is disposed on the inner surface of the first wall, the rails being substantially parallel to a first longitudinal axis of the first chamber. A slider guide is disposed on the inner surface of the first wall between at least two of the rails. The abdominal exerciser further includes a second body member having a second chamber at least partially surrounded along its length by a second wall having inner and outer surfaces. The second body member further includes an end cap formed at one end of the second chamber, and the end cap includes a second anchor notch formed therein. The second body member is received by the first chamber of the first body member such that the outer surface of the second body member engages the plurality of rails within the first chamber. A slider slot is formed in the wall of the second body member substantially parallel to a second longitudinal axis of the second chamber, and the slider slot receives the slider guide to permit relative motion of the first and second body members in a first direction parallel to the first and second longitudinal axes and to prevent relative motion of the first and second body members in directions substantially perpendicular to the first direction. An anchor body is positioned within the second chamber of the second body member and is connected to the slider guide of the first member. The anchor body includes a first anchor notch, and a single resistance member is operably attached to the first anchor notch and the second anchor notch to resist but not prevent relative motion of the first body member and the second body member in the first direction.

In accordance with another embodiment of the present invention, an abdominal exerciser is provided and includes a first body member having a first chamber at least partially surrounded along its length by a first wall having inner and outer surfaces. The abdominal exerciser further includes a second body member having a second chamber at least partially surrounded along its length by a second wall having inner and outer surfaces. The second body member includes an end cap formed at one end of the second chamber, and a second anchor notch is formed in the endcap. The second body member is slidingly received by the first chamber of the first body member such that the first and second body members are capable of relative motion in a first direction between an uncompressed position and a compressed position. A slider slot is formed in the wall of the second body member, and an anchor body is positioned within the second chamber of the second body member and connected to the first member through the slider slot. The anchor body includes opposing ramp members attached to a base plate, each opposing ramp member having a graduated upper edge transitioning from the base plate at one end of the anchor body to an end plate at an opposite end of the anchor body. The end plate of the anchor body includes a first anchor notch. A resistance member is configured for positioning in an engaged state in which a first end of the resistance member engages the second anchor notch and a second end of the resistance member engages the first anchor notch to resist but not prevent relative motion of the first and second body members in the first direction. The resistance member is further configured for positioning in a disengaged state in which the first end of the resistance member resides in the first chamber and the second end of the resistance member engages the second anchor notch. When the resistance member is in the disengaged state, moving the first and second body members into the compressed position causes the ramp members of the anchor body to bias the second end of the resistance member outward for easier grasping by a user.

Other objects, features, and advantages of the present invention will become apparent with reference to the drawings and detailed description that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a compact abdominal exercise apparatus according to an embodiment of the present invention in an uncompressed position;

FIG. 2 depicts a front view of the compact abdominal exercise apparatus of FIG. 1;

FIG. 3 illustrates a back view of the compact abdominal exercise apparatus of FIG. 1;

FIG. 4 depicts an exploded perspective view of the compact abdominal exercise apparatus of FIG. 1;

FIG. 5 illustrates an enlarged exploded perspective view of a portion of the compact abdominal exercise apparatus of FIG. 1 illustrated from a different angle than that of FIG. 4;

FIG. 6 depicts a partially exploded perspective view of the compact abdominal exercise apparatus of FIG. 1 with the slideable cover member engaged on the upper support member;

FIG. 7 illustrates a front view of an upper support member of the abdominal exercise apparatus of FIG. 1;

FIG. 8 depicts a front view of a lower support member of the abdominal exercise apparatus of FIG. 1;

FIG. 9 illustrates an enlarged front view of the abdominal exercise apparatus of FIG. 1 in the uncompressed position, the abdominal exercise apparatus including a protective cover which is illustrated in an open position and a resistance member which is engaged to both the upper and lower support members;

FIG. 10 depicts a front view of the abdominal exercise apparatus of FIG. 1 with the device illustrated in a partially compressed position;

FIG. 11 illustrates a perspective view of the exercise apparatus of FIG. 1 in a compressed position;

FIG. 12 depicts a graphical representation of the relationship between load and EMG activity of the left oblique muscle of a group of test subjects (plus or minus standard deviation) for left bending abdominal exercises;

FIG. 13 illustrates a chart showing the average muscle activity of the left oblique muscle for a group of test subjects during each of three exercises, the chart showing EMG activity expressed as a percent of the EMG during maximum strength determinations;

FIG. 14 depicts a chart showing the average muscle activity of the right oblique muscle for a group of test subjects during each of three exercises, the chart showing EMG activity expressed as a percent of the EMG during maximum strength determinations;

FIG. 15 illustrates a chart showing the average muscle activity of the left rectus muscle for a group of test subjects during each of three exercises, the chart showing EMG activity expressed as a percent of the EMG during maximum strength determinations;

FIG. 16 depicts a chart showing the average muscle activity of the right rectus muscle for a group of test subjects during each of three exercises, the chart showing EMG activity expressed as a percent of the EMG during maximum strength determinations;

FIG. 17 illustrates a chart showing the work performed by the left oblique muscle during exercise at the heaviest workload during left and right rotational exercises using the abdominal exerciser of the present invention with three different resistance members, the chart further illustrating a comparison to a supine abdominal crunch;

FIG. 18 depicts a chart showing the work performed by the right oblique muscle during exercise at the heaviest workload during left and right rotational exercises using the abdominal exerciser of the present invention with three different resistance members, the chart further illustrating a comparison to a supine abdominal crunch;

FIG. 19 illustrates a chart showing the work performed by the left rectus muscle during exercise at the heaviest workload during left and right rotational exercises using the abdominal exerciser of the present invention with three different resistance members, the chart further illustrating a comparison to a supine abdominal crunch; and

FIG. 20 depicts a chart showing the work performed by the right rectus muscle during exercise at the heaviest workload during left and right rotational exercises using the abdominal exerciser of the present invention with three different resistance members, the chart further illustrating a comparison to a supine abdominal crunch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

Referring to FIGS. 1-11, an abdominal exerciser 100 according to an embodiment of the present invention includes a first, or lower, body member 110 adapted to engage a seating platform on which a user is seated and a second, or upper, body member 150 adapted to engage a portion of the user's body above the abdomen. The lower body member 110 includes a proximal end 112 and a distal end 114. The lower body member 110 includes a first chamber 118 that is at least partially surrounded along its length by a first wall 120 that preferably extends substantially the entire distance from the proximal end 112 to the distal end 114. A pair of lateral wing members 124 is integrally connected to opposing sides of the first wall 120. The lateral wing members 124 and first wall 120 integrally connect to a base 128 at the distal end 114 of the lower body member 110. A plurality of vents 132 may be disposed in the first wall 120 to allow fluid communication of air between the first chamber 118 and the ambient environment surrounding the abdominal exerciser 100.

The first wall 120 of the lower body member 110 includes an inner surface 136 and an outer surface 138. A plurality of rails 140 may be positioned on the inner surface 136 of the first wall 120 substantially parallel to a first longitudinal axis 142 (see FIG. 4) of the first chamber 118. Each of the rails extends from the inner surface 136 into the first chamber 118 to provide a raised, or elevated, surface. In one embodiment, the plurality of rails 140 comprises a pair of rails, and a slider guide 144 is positioned substantially parallel to and between the rails 140. The slider guide 144 also extends from the inner surface 136 into the first chamber 118; and preferably, the slider guide 144 extends further into the first chamber 118 than the rails 140.

The first wall 120 further includes an access opening 146 that exposes and allows access to a portion of the first chamber 118. A pair of recessed rails 147 may be disposed on opposing sides of the access opening 146. A recessed region 148 of the first wall 120 is positioned at the distal end 114 of the lower body member 110. The first wall 120 may be thinner in the recessed region 148, and the outer surface 138 in the recessed region 148 is offset from the outer surface 138 in areas of the first wall 120 immediately adjacent the recessed region 148. A pair of detents 149 may be disposed on the outer surface 138 in the recessed region 148 on opposing sides of the first wall 120.

The upper body member 150 includes a proximal end 152 and a distal end 154. The proximal end 152 includes a pair of forked extension members 158 extending divergently outward from one another, each extension member 158 being adapted for gripping by a hand of the user. The forked extension members 158 may be integrally connected to a second wall 162 that at least partially surrounds a second chamber 166 extending from the forked extension members 158 toward the distal end 154. The second wall includes an outer surface 168 and an inner surface 169. In the embodiment illustrated in FIGS. 1-11, the second wall 162 has a generally octagonal cross-section, but a person of ordinary skill in the art will recognize that the second wall 162 could have a cross-section of any shape, including, without limitation, round, triangular, square, rectangular, or other polygonal or free-form cross-sections. The second chamber 166 extends longitudinally along a longitudinal axis 170 (see FIG. 4) that preferably bisects an angle formed between the extension members 158. The upper body member 150 further includes an end cap 174 integrally connected to the second wall 162 at the distal end 154 of the upper body member 150. The end cap 174 includes a second anchor notch 178 formed therein. Upper body member 150 further includes a resistance opening 180 formed in a portion of second wall 162.

Referring more specifically to FIGS. 3 and 9, upper body member 150 further may include a slider slot 184 formed in the second wall 162. The slider slot 184 preferably is oriented substantially parallel to the longitudinal axis 170 of the second chamber 166.

Referring more specifically to FIGS. 1, 6, 9, and 10, the upper body member 150 may be connected to the lower body member 110 such that the second wall 162 of the upper body member 150 is slidingly received by the first chamber 118 of the lower body member 110. When the upper and lower body members 150, 110 are engaged, the slider slot 184 of the upper body member 150 receives the slider guide 144 of the lower body member 110. Together, the first wall 120 of the lower body member 100 and the slider slot 184 comprise a constraint assembly, which by constraining the second wall 162 and the slider guide 144, permit relative motion of the upper and lower body members 150, 110 in a first direction parallel to the longitudinal axes 142, 170 and prevent relative motion of the upper and lower body members 150, 110 in directions perpendicular to the first direction. When received by the first chamber 118, the outer surface 168 of the second wall 162 engages the plurality of rails 140 within the first chamber 118. The rails 140 allow the outer surface 168 of the second wall 162 to be offset from the inner wall 136 of the first chamber 118, thereby reducing the area of contact and thus the friction between the upper and lower body members 150, 110.

After placing the distal end 154 of the upper body member 150 within the first chamber 118 of the lower body member 110 such that the slider guide 144 is received by the slider slot 184, an anchor body 210 is connected to the slider guide 144 (and thus the lower body member) using fasteners 212 such as screws, bolts, rivets, adhesive, or any other fastening means. The anchor body 210 prevents the slider guide 144 from becoming disengaged from the slider slot 184, which keeps the upper body member 150 engaged with the lower body member 110. A spacer 216 may be positioned between the anchor body 210 and the slider guide 144 to offset the anchor body 210 from the inner surface 169 of the second wall 162.

Referring more specifically to FIG. 5, the anchor body 210 includes opposing ramp members 220 connected to a base plate 222. Each opposing ramp member 220 includes a graduated upper edge 226 that rises from the base plate 222 at one end of the anchor body 210 to an end plate 228 at an opposite end of the anchor body 210. A first anchor notch 229 is formed in the end plate 228 of the anchor body 210. The anchor body 210 is oriented within the second chamber 166 such that the end of the anchor body 210 opposite the end plate 228 is adjacent to the second anchor notch 178 (see FIG. 9). Preferably, the abdominal exerciser 100 is sold to consumers in an assembled state in which the anchor body 210 has already been attached to the slider guide 144, and the upper and lower body members 150, 110 are already slidingly engaged.

When the upper and lower body members 150, 110 are connected, the resistance opening 180 of the upper body member 150 permits access to a resistance cavity 230, which is generally located within the second chamber 166 between the first anchor notch 229 and the second anchor notch 178. It should be recognized that, as the abdominal exerciser 100 is compressed, the resistance cavity 230 may extend beyond the confines of the resistance opening 180 since the first anchor notch 229 of the anchor body 210 travels into the second chamber 166 past the resistance opening 180.

A resistance member 240 is disposed within the resistance cavity 230 and is operably connected between the first and second anchor notches 229, 178. The resistance member 240 includes an elastic cord 242 connected to two anchor cylinders 246. The cylinders 246 each have a reduced diameter portion 248. The reduced diameter portions 248 slip into first and second anchor notches 229, 178 (see FIGS. 4 and 5). When installed, the elastic cord 242 resides in the resistance cavity 230. The primary purpose of the resistance member 240 is to resist, yet not prevent, relative motion of the upper body member 150 and the lower body member 110 in the first direction. When the upper body member 150 is compressed longitudinally into lower body member 110 (FIG. 11), the elastic cord 242 stretches, providing resistance to the motion (see FIG. 10).

The abdominal exerciser 100 further includes a protective cover 310 having a sleeve 312 integrally connected to an access panel 314. The sleeve 312 preferably includes a cross-sectional shape similar to that of the second wall 162 of the upper body member 150. The upper body member 150 is received by the sleeve 312 such that the sleeve 312 can slide in either direction along the upper body member 150 parallel to the longitudinal axis 170. The protective cover 310 may be placed in an open position (see FIGS. 9 and 10) to allow access to the resistance cavity 230. Alternatively, the protective cover 310 may be placed in a closed position (see FIGS. 1-3) to substantially enclose the resistance cavity 230. In the closed position, the access panel 314 blocks the access opening 146 provided on the lower body member 110. The access panel 314 is supported by the pair of recessed rails 147 on each side of the access opening 146. In the closed position, the sleeve 312 of the protective cover 310 is positioned over the recessed region 148 of the first wall 120, and an inner surface of the sleeve 312 engages the detents 149 of the recessed region 148 to secure the protective cover 310 in the closed position. Alternatively, detents or other locking mechanisms could be provided on the inner surface of the sleeve 312 to engage complimentary locking mechanisms on the recessed region 148.

A person of ordinary skill in the art of the present invention will recognize that the protective cover 310 could engage the access opening 146 in alternative ways to those illustrated in FIGS. 1-11. For example, in another embodiment of the present invention, a recessed rail may be disposed at an end of the access opening 146 opposite the proximal end 112 of the lower body member 110. The recessed rail may include an indentation to accept a detent positioned on the access panel 314 of the protective cover 310. Together, the indentation and detent allow the protective cover 310 to be secured in the closed position.

In operation, the abdominal exerciser is provided to exercise the abdominal muscles of the user and is uniquely designed to do so by allowing the user to perform forward or oblique crunches when the distal end of the lower body member is positioned against a seating platform on which the user is seated. A person of ordinary skill in the art of the invention will recognize that the seating platform could include a chair, a stool, a table, a floor, or any other surface or platform on which a user could be seated. When no external forces are applied to the abdominal exerciser and the resistance member is engaged, the abdominal exerciser is positioned in an uncompressed position as illustrated in FIG. 1. The user performs oblique crunches with the device by first grasping the extension members 158 on the upper body member 150 and then positioning the lower body member 110 against the seating platform beside the thigh or hip of the user on either side of the user's body. The user then contracts his or her abdominal muscles in an attempt to compress the upper and lower body members 150, 110 into a compressed position (see FIG. 11). As the upper and lower body members 110, 150 are compressed, the user is forced to slightly twist his or her upper body, since the lower body member 110 is positioned lateral to the user's hip or thigh. This positioning allows the user to accomplish an oblique crunch, which, as explained in more detail below, increases the amount of work performed by the user's abdominal muscles.

In addition to the oblique crunches described above, the abdominal exerciser 100 further can be used to perform forward crunches by placing the lower body member 110 against the seating platform and crunching forward without twisting the user's upper body. Alternatively, the user could position his body in a supine position on a floor or other surface and perform crunches with the lower body member 110 anchored against either of the user's thighs.

As the abdominal exerciser is moved by the user from the uncompressed position to the compressed position, the second wall 162 of the upper body member 150 slides within the first chamber 118 of the lower body member 110 in the first direction, which is parallel to the longitudinal axes 142, 170. Friction between the upper and lower body members 150, 110 is reduced, since the upper body member 150 engages and slides upon the rails 140. The slider guide 144 tracks within the slider slot 184 and prevents relative motion of the upper and lower body member 150, 110 in directions substantially perpendicular to the first direction. Movement in these lateral directions is further prevented by the upper body member being laterally constrained by the first wall 120 of the lower body member 110. The slider guide 144 further limits the range of motion of the upper and lower body members 150, 110 between the uncompressed and compressed positions. More specifically, when the abdominal exerciser 100 is in the uncompressed position, the slider guide 144 contacts one end of the slider slot 184. When the abdominal exerciser 100 is placed in a compressed position, the slider guide 144 contacts another end of the slider slot 184.

The abdominal exerciser 100 is sized to permit comfortable and effective oblique crunches or forward crunches, but particularly oblique crunches. Oblique crunches performed with the abdominal exerciser 100 of the present invention increase and improve the workout obtained by a user when compared to traditional crunches. The length of the abdominal exerciser is longer than traditional abdominal exercisers, since the device is meant to be laterally adjacent to the user's hip or thigh and anchored upon the seating platform on which the user is seated. Traditional abdominal exercisers were placed directly on one or both of the user's thighs, which resulted in much less rotation of the upper body during oblique crunching exercises. The increased length of the abdominal exerciser 100 is based on anthropometric data associated with average-sized humans. The seated acromion height of a person represents the distance between a surface on which the person is seated and the acromial process, which is located near the top of the person's shoulder. By increasing the length of both the upper and lower body members to approximate the seated acromion height of a human person, the abdominal exerciser 100 is sized to permit comfortable and effective oblique crunches when the lower body member 110 is placed against the seating platform on which the user is seated. More specifically, the upper and lower body members 150, 110 are sized such that an average-sized male or female may place the lower body member against the seating platform and then grasp the forked extension members at some point along the length of the extension members such that the user's hands are positioned at a height above the seating platform that is substantially level with a region between the user's nose and shoulder.

The length “A” of the abdominal exerciser 100 (see FIG. 2) is, preferably in the uncompressed condition of the exerciser, between twenty-two and twenty-eight inches, more preferably between twenty-three and a half and twenty-seven inches, and most preferably between twenty-five and twenty-six inches. Preferably, the length “A” of the exerciser in the compressed position from the proximal end of the upper support member to the distal end of the lower support member is greater than seventeen inches, more preferably eighteen or more inches, and most preferably nineteen or more inches. The compression ratio of the abdominal exerciser 100, which is defined as the difference between the uncompressed and compressed lengths of the abdominal exerciser divided by the uncompressed length, is preferably greater than 0.20, and more preferably about 0.24. This compression ratio is greater than compression ratios for traditional abdominal exercisers such as the device described by U.S. Pat. No. 6,712,742.

The width of the distal end 114 of the lower body member 110 is designed to more easily permit oblique crunches. In prior art exercisers of this type, this distal end was too large for this function. Preferably, the width “B” of the base 128 (see FIG. 2) is between three inches and eleven inches, more preferably between five inches and nine inches, and most preferably between six inches and eight inches.

When the abdominal exerciser is not in use, or when the abdominal exerciser is being shipped, the resistance member 240 can be disengaged by first opening the protective cover 310 to allow access to the resistance cavity 230. The resistance member 240 is disengaged by removing the reduced diameter portion 248 of the anchor cylinder 246 from the first anchor notch 229 and sliding the resistance member 240 toward the lower body member 110 such that one end of the resistance member 240 is disposed within the first chamber 118 and the other end of the resistance member 240 is disposed within the resistance cavity 230 between the first and second anchor notches 229, 178. In this disengaged position, the elastic cord 242 passes through the second anchor notch 178. Since the resistance member 240 is no longer engaged to both the first and the second anchor notches 229, 178, no resistance is provided by the elastic cord 242 relative to movement of the upper and lower body members 150, 110. The upper and lower body members 150, 110, therefore, can be placed and stored in the compressed position. This is especially useful for storing the abdominal exerciser in small spaces between uses, or in shipping the device to a retail store or consumer. Because the abdominal exerciser takes up less space in the compressed position, a smaller box may be used to ship the device, thereby reducing shipping costs.

As previously described, the anchor body 210 includes opposing ramp members 220, the ramp members 220 including graduated upper edges 226 that rise from the base plate 222 at one end of the anchor body 210 to the end plate 228 at the opposite end of the anchor body 210. The ramp members 220 aid a user in engaging the resistance member 240 when the abdominal exerciser has been stored in a compressed position with the resistance member 240 disengaged. The ramp members 220 are positioned and shaped such that the end of the resistance member 240 disposed within the resistance cavity 230 may be biased upward from the resistance cavity 230 when the abdominal exerciser 100 is moved from the compressed position to the uncompressed position with the protective cover 310 in an open position. As the upper and lower body members 150, 110 approach the uncompressed position, the anchor cylinder 246 disposed between the first and second anchor notches 229, 178 engages the graduated upper edges 226 of the ramp members 220 and travels upward along the graduated upper edges 226 until the anchor cylinder 246 is positioned just above the end plate 228 and protrudes from the resistance cavity 230. This positioning of the anchor cylinder 246 allows the user to easily grasp the anchor cylinder 246 and slide the reduced diameter portion 248 of the anchor cylinder 246 into the first anchor notch 229, thereby again placing the resistance member 240 in the engaged position.

A person of ordinary skill in the art will recognize that many of the parts and functions described above with respect to the upper body member 150 can be interchanged with the parts and functions associated with the lower body member 110. For example, the sliding cover member 150 could be slidingly disposed on the lower body member 110 and slid in the opposite direction to expose the resistance cavity. Furthermore, the device could be designed so that the lower body member 110 slides within the upper body member 150, thereby potentially altering the orientation and attachment characteristics of the anchor body 210.

Testing Summary

Twenty-nine male and female subjects in the age range of 17 to 49 years old were examined to evaluate the effectiveness of the abdominal exerciser described herein on muscle use during abdominal flexion exercises. Subjects were a mixture of fit and sedentary individuals. They were engaged in exercise on the abdominal exerciser in the seated position, and exercise was compared to supine conventional crunches without the machine. The muscles studied were the rectus abdominus and the external oblique muscles. To evaluate the use of the muscles, EMG electrodes were placed on the right and left rectus abdominus muscles and the right and left external oblique muscles. The relationship between workload on the portable abdominal machine and EMG of the rectus abdominus and obliques was linear. At the heaviest workload, work accomplished (duration x EMG amplitude) was 1.9 times higher than the work performed in an abdominal crunch for the rectus abdominus muscles and 4.4 times the work for the oblique muscles in the abdominal exerciser compared to traditional abdominal crunches for the oblique muscles. These differences were significant (p<0.01). Thus, the abdominal exerciser provided a good reliable form of exercise for the abdominal and oblique muscles with one simple movement and in the seated position.

Test Protocol

Twenty-nine subjects (male=14 and female=15) participated in these experiments. This population was chosen based on power analysis of the variance to provide reliability in the analysis. Their ages ranged between 17 and 49 years old. The general characteristics of the subjects are shown in Table 1. All experimental protocols and procedures were approved by the Human Review Committee at Azusa Pacific University, and all subjects signed a statement of informed consent acknowledging that they were fully aware of the purposes and procedures of the project. TABLE 1 General Characteristics of Subjects Age(years) Weight(kg) Height(cm) Mean 38.3 73.3 167.3 SD 13.4 15.3 11.8

Exercise device—The exercise machine used in the test was the abdominal exerciser described herein. The device consisted of a rectangular plastic frame with an elastic band on the inside to adjust resistance. Resistance could be increased in 3 different stages so that it became increasingly more difficult to compress the frame (30, 50, or 75 lbs) (13.6, 22.7, or 35 kg). The upper part of the frame was placed in the subject's hands with the base of the machine on the seat to the left or right of the subject. The device was then compressed fully, thereby exercising the obliques.

EMG—The electromyogram (EMG) was recorded through two bipolar vinyl adhesive electrodes (silver silver-chloride) with an active surface area of 0.5 cm². One electrode was placed over the belly of the active muscle. The second electrode was placed 2 cm distal to the active electrode. EMG was amplified using a 4-channel amplifier whose frequency response was flat from DC to 1000 Hz. The common mode rejection ratio of the amplifier was greater than 120 Db. The EMG was then digitized at 1000 samples/second by a Biopac (Biopac Corp., Santa Barbara, Calif.) 16 bit analog-to-digital converter and displayed and stored on an IBM computer for later analysis. The amplitude of EMG was assessed by digitizing and half-wave rectifying the raw data and calculating the mean voltage of rectified EMG.

Measurement of strength of the abdominal muscles—Isometric strength of the abdominal muscles was measured in the seated position. To accomplish this, subjects sat with the hips at an angle of 90°. A modified exercise device with strain gauges was used to assess maximum strength. Strength was measured in the forward, left, and right rotation directions. The strain gauge was linear from 0-200 kg of force. The output of the transducer was amplified with a strain gauge conditioner amplifier with a gain of 1000 and digitized in a Biopac 16 bit analog-to-digital converter and displayed and stored on an IBM computer. The output was stored and analyzed as the average strength over the middle of a three-second contraction. Strength was measured by an isometric contraction for three seconds. At least one minute was allowed between each of three contractions to allow for recovery.

The tests proceeded by first assessing EMG during a maximum effort as well as strength during flexion, both facing forward and while the trunk of the user was rotated to the left and right as described above. Next, EMG was assessed over the left and right rectus abdominus and left and right external oblique muscles during the following exercises:

-   -   1. The abdominal exerciser was placed on the side of the subject         with the base on the chair. The arms were placed on the handles         so the body of the subject was rotated to the left, to perform         the oblique side-bending exercise. The machine was depressed         fully over a two to three second period. The arms were then         reversed to the right hand side and the exercise repeated.     -   2. A standard crunch was performed while laying supine on the         floor with the hip and knees bent to approximately 45 degrees         and the arms folded and crossed over the chest. No device was         used and the subject lifted their shoulders high enough for his         or her scapulae to clear the floor.     -   3. Finally, for four sets of resistive bands, the force to         depress the bands in the machine was tested to verify the         tension and linearity of the machines.

Each exercise was performed over a three-minute period while EMG was measured. All exercises were repeated in part 1 at three loads (30, 50, and 75 lbs)(13.6, 22.7, and 34 kg).

Data Analysis and Results

Statistical analysis involved the calculations of means, standard deviations, analysis of variance (ANOVA), and T tests. The level of significance was p<0.05. EMG was analyzed over three-second periods through the digitized EMG data.

Muscle strength during flexion of the abdominal muscles in the forward facing direction and during right and left rotation exercises is shown in Table 2. This table displays the mean±the respective standard deviation for the group of subjects. As can be seen in this table, muscle strength was greatest for flexion and lowest for right and left rotation. TABLE 2 Strength of the Subjects Strength(kg) Flexion Right Rotation Left Rotation Mean 65.8 48.5 43.9 SD 12.5 8.0 9.1

The force necessary to compress the abdominal exercise machine fully against the four different sets of resistance bands that were tested is shown below in Table 3. TABLE 3 Variability in Resistance of Exercise Device to Fully Depress the Machine(kg) by Band Color Band Color Trial Yellow Orange Red 1 14.5 18.3 42.1 2 15.8 27.6 32.3 3 22.4 26.2 34.4 4 19.8 23.8 41.6 Mean 18.1 24.0 37.6 SD 3.6 4.1 5.0

The average force to depress the abdominal exerciser to the compressed position for the three colors of resistance bands was 18.1, 24.0, and 37.6 kg. This corresponded to a load of 39, 52, and 82 lbs. for the three bands. For the group of subjects as a whole, the maximum resistance of the device was less than the maximum strength of the subjects; but for some subjects, the maximum resistance of the device did exceed the maximum strength of the subjects. The average strength of the men for right rotation, for example, was 51.1 kg, a force more than adequate to depress the machine fully, whereas for the women, maximum strength was 35.6 kg, making it impossible for some women to fully depress the machine. However, the data was averaged into the results below to the fullest extent that the subjects could depress the machine.

The EMG activity during flexion of the abdominal muscles with use of the abdominal machine was linearly related to the workload. For example, as shown in FIG. 12, for left-bending abdominal exercises, as the resistance of the abdominal exerciser was increased by changing the bands, the EMG activity of the muscles likewise increased. However, the variation from one subject to the next was large as shown by the large standard deviations in FIG. 12. Therefore, EMG, rather than being expressed as an absolute value, was normalized in the remainder of the analysis as a percent of the maximum muscle activity during the maximum strength determinations. This allowed for differences in EMG activity between one individual and another.

The average normalized muscle activity in the left oblique, right oblique, left rectus abdominus, and right rectus abdominus muscles as measured during each of three exercises are shown in FIGS. 13-16. The charts of FIGS. 13-16 each show muscle activity from one of the four muscles during left- and right-side bending exercise and standard abdominal crunches. The greatest muscle activity was during exercise with the red band inserted in the abdominal exerciser. Here, as shown in FIGS. 15 and 16, muscle activity was still ⅓ higher for the rectus abdominus than was seen for standard crunches. For the red band, the greatest difference in EMG activity between crunches and use of the exercise machine was for the oblique. Oblique activity for the left and right obliques was 49+/−11% and 34+/−12% of maximum EMG activity during work on the machine against the highest load for rotation to the left, whereas, for example, during abdominal crunches, it was 19±7% and 26±12% of maximum muscle. Thus, oblique activity was more than twice as high as seen during standard crunches. Even for exercise against the middle load band (orange band), rectus and oblique activity was similar to the standard crunches. For the yellow band, muscle activity was about one-half that of crunches.

Not only was the EMG activity higher, but the duration of the exercise was longer using the exercise machine compared to abdominal crunches. The average duration of the exercise for all subjects was 4.04±1.92 seconds for the left rotation exercise, 3.92±1.52 seconds for the right rotation exercise, and 2.04±0.92 sec for the abdominal crunches. Thus, with a significantly longer duration of the exercise on the machine versus standard abdominal crunches, work would also be greater for the machine on a per crunch basis. By multiplying the product of time x EMG derived muscle activity, a work index was computed. This work index data is shown in FIGS. 17-20.

When work was computed for the left obliques (FIG. 17), right obliques (FIG. 18), left rectus abdominus (FIG. 19), and right rectus abdominus (FIG. 20) muscles during rotating left and right exercises with the abdominal exerciser versus supine crunches, the results show that work was much higher for any given exercise using the abdominal exerciser than supine crunches. As can be seen in FIGS. 17-20, the total work for exercise against the red band was up to 4.0 times higher on the cross crunch machine than for crunches. For the obliques, work was 4.42 times greater during side exercises vs. standard crunches. For the rectus abdominus muscles, work was 1.7 times greater. This same relationship was seen for the other bands but, with a lighter load, work was proportionally less. For the orange band, work for the obliques was still 3 times greater than for standard crunches, while for the rectus abdominus it was about equal to standard crunches. Total work of all the muscles was over twice as high on the abdominal crunch machine vs. standard crunches. For the yellow resistance band, work was about equal for the obliques between the two types of exercise and 20% less for the rectus abdominus during cross crunch exercise compared to standard crunches.

There has been described herein a compact abdominal exercise apparatus that has a quick-change resistive force with an elastic member that is more effective, efficient, and ergonomic than traditional compact abdominal exercisers. It should be apparent from the foregoing that an invention having significant advantages has been provided. While the invention is shown in only a few of its forms, it is not just limited but is susceptible to various changes and modifications without departing from the spirit thereof. 

1. A compact abdominal exercise apparatus comprising: (a) a lower body member adapted to engage a seating platform on which a user is seated; (b) an upper body member adapted to engage a portion of the user above the abdomen; (c) a constraint assembly connecting said lower body member and said upper body member, said constraint assembly permitting relative motion of said lower body member and said upper body member in a first direction along a line connecting said lower body member and said upper body member and preventing relative motion of said lower body member and said upper body member in directions perpendicular to said first direction; (d) a first anchor notch operably associated with the lower body member; (e) a second anchor notch operably associated with the upper body member; (f) a resilient cord connectable between said first anchor notch and said second anchor notch to provide resistance to relative motion of said lower and upper body members in said first direction; and (g) wherein the length of said exercise apparatus from a distal end of said lower body member to a proximal end of said upper body member is such as to permit oblique crunches when said lower body member engages the seating platform.
 2. The compact abdominal exercise apparatus of claim 1 wherein said length is between twenty-two and twenty-eight inches.
 3. The compact abdominal exercise apparatus of claim 1 wherein said length is between twenty-three and a half and twenty-seven inches.
 4. The compact abdominal exercise apparatus of claim 1 wherein said length is between twenty-five and twenty-six inches.
 5. The compact abdominal exercise apparatus of claim 1 wherein the longest dimension of said lower body member perpendicular to said length is between three inches and eleven inches.
 6. The compact abdominal exercise apparatus of claim 1 wherein the longest dimension of said lower body member perpendicular to said length is between five inches and nine inches.
 7. The compact abdominal exercise apparatus of claim 1 wherein the longest dimension of said lower body member perpendicular to said length is between six inches and eight inches.
 8. The compact abdominal exercise apparatus of claim 1, further comprising a slideable protective cover for substantially enclosing said resilient cord.
 9. A compact abdominal exercise apparatus comprising: (a) a lower body member adapted to engage a portion of a seating platform on which a user is seated; (b) an upper body member adapted to engage a portion of the user's body above the abdomen, the upper body member connected to the lower body member such that relative motion of said lower body member and said upper body member is permitted in at least a first direction along a longitudinal line connecting said lower body member and said upper body member and prevented in directions perpendicular to said first direction; (c) a resistance member operably attached to the lower body member and the upper body member to resist but not prevent relative motion of said lower body member and said upper body member in said first direction, said resistance member contained within a resistance cavity; and (d) a protective cover slidingly disposed on at least one of the upper body member and the lower body member to substantially enclose said resistance cavity when said protective cover is placed in a closed position and to allow access to said resistance cavity when said protective cover is placed in an open position.
 10. The compact abdominal exercise apparatus of claim 9 wherein placing said protective cover in the open position allows said resistance member to be disengaged from providing resistance to relative motion of the upper and lower body members.
 11. The compact abdominal exercise apparatus of claim 9 wherein the length of said exercise apparatus from a distal end of said lower body member to a proximal end of said upper body member is such as to permit oblique crunches when said lower body member engages the seating platform.
 12. A compact abdominal exercise apparatus comprising: (a) a first body member having a first chamber at least partially surrounded along its length by a first wall having inner and outer surfaces; (b) a plurality of rails disposed on the inner surface of the first wall substantially parallel to a first longitudinal axis of the first chamber; (c) a slider guide disposed on the inner surface of the first wall between at least two of the rails; (d) a second body member having a second chamber at least partially surrounded along its length by a second wall having inner and outer surfaces, the second body member further having an end cap formed at one end of the second chamber, the end cap having a second anchor notch, the second body member being received by the first chamber of the first body member such that the outer surface of the second body member engages the plurality of rails within the first chamber; (e) a slider slot formed in the wall of the second body member substantially parallel to a second longitudinal axis of the second chamber, the slider slot receiving the slider guide to permit relative motion of the first and second body members in a first direction parallel to the first and second longitudinal axes and to prevent relative motion of the first and second body members in directions substantially perpendicular to the first direction; (f) an anchor body positioned within the second chamber of the second body member and connected to the slider guide of the first body member, the anchor body having a first anchor notch; and (g) a single resistance member operably attached to the first anchor notch and the second anchor notch to resist but not prevent relative motion of the first body member and the second body member in the first direction.
 13. The compact abdominal exercise apparatus of claim 12 wherein said resistance member is contained within a resistance cavity, and said exercise apparatus further comprises a protective cover slidingly disposed on at least one of the first body member and the second body member to substantially enclose said resistance cavity when said protective cover is placed in a closed position and to allow access to said resistance cavity when said protective cover is placed in an open position.
 14. The compact abdominal exercise apparatus of claim 12 wherein: the first body member is adapted to engage a seating platform on which a user is seated; and the second body member is adapted to engage a portion of the user's body above the abdomen.
 15. The compact abdominal exercise apparatus of claim 14 wherein the length of said exercise apparatus from a distal end of said first body member to a proximal end of said second body member is such as to permit oblique crunches when said first body member engages the seating platform.
 16. A compact abdominal exercise apparatus comprising: (a) a first body member having a first chamber at least partially surrounded along its length by a first wall having inner and outer surfaces; (b) a second body member having a second chamber at least partially surrounded along its length by a second wall having inner and outer surfaces, the second body member further having an end cap formed at one end of the second chamber, the end cap having a second anchor notch, the second body member being slidingly received by the first chamber of the first body member, the first and second body members being capable of relative motion in a first direction between an uncompressed position and a compressed position; (c) a slider slot formed in the wall of the second body member; (d) an anchor body positioned within the second chamber of the second body member and connected to the first body member through the slider slot, the anchor body having opposing ramp members attached to a base plate, each opposing ramp member having a graduated upper edge transitioning from the base plate at one end of the anchor body to an end plate at an opposite end of the anchor body, the end plate having a first anchor notch; (e) a resistance member configured for positioning in an engaged state in which a first end of the resistance member engages the second anchor notch and a second end of the resistance member engages the first anchor notch to resist but not prevent relative motion of the first body member and the second body member in the first direction, the resistance member further configured for positioning in a disengaged state in which the first end of the resistance member resides in the first chamber and the second end of the resistance member engages the second anchor notch; and (f) wherein the ramp members of the anchor body bias the second end of the resistance member outward for easier grasping by a user when the resistance member is in a disengaged state and the first and second body members are moved into the compressed position.
 17. The compact abdominal exercise apparatus of claim 16 wherein said resistance member is contained within a resistance cavity, and said exercise apparatus further comprises a protective cover slidingly disposed on at least one of the first body member and the second body member to substantially enclose said resistance cavity when said protective cover is placed in a closed position and to allow access to said resistance cavity when said protective cover is placed in an open position.
 18. The compact abdominal exercise apparatus of claim 16 wherein: the first body member is adapted to engage a seating platform on which a user is seated; and the second body member is adapted to engage a portion of the user's body above the abdomen.
 19. The compact abdominal exercise apparatus of claim 18 wherein the length of said exercise apparatus from a distal end of said first body member to a proximal end of said second body member is such as to permit oblique crunches when said first body member engages the seating platform.
 20. The compact abdominal exercise apparatus of claim 16, further comprising a plurality of rails disposed on the inner surface of the first wall of the first body member to engage the outer surface of the second wall of the second body member within the first chamber. 